Light emitting devices, such as organic or inorganic electroluminescent devices, are useful in a variety of display, lighting, and other applications. Generally, these light emitting devices include one or more devices layers, including at least one light emitting layer, disposed between two electrodes (an anode and a cathode). A voltage drop or current is provided between the two electrodes, thereby causing a light emitting material, which can be organic or inorganic, in the light emitting layer to luminesce. Typically, one or both of the electrodes is transparent so that light can be transmitted through the electrode to a viewer or other light receiver.
An electroluminescent device may be constructed such that it is either a top emitting device or a bottom emitting device. In a top emitting electroluminescent device, the light emitting layer or layers are positioned between the substrate and a viewer. In a bottom emitting electroluminescent device, a transparent or semitransparent substrate is positioned between the light emitting layer or layers and the viewer.
In a typical color electroluminescent display, one or more electroluminescent devices can be formed on a single substrate and arranged in groups or arrays. Several approaches exist for producing a color electroluminescent display. For example, one approach includes an array having red, green, and blue electroluminescent device subpixels placed next to each other. Another approach, for example, uses color conversion to produce a color electroluminescent display. Displays that utilize color conversion can include electroluminescent devices that emit light in a narrow band, e.g., blue light. Each color conversion electroluminescent device also includes one or more color conversion elements in optical association with the electroluminescent device such that the emitted light (e.g., blue light) is converted, e.g., to red light by a red color conversion element and green light by a green color conversion element.